A Schottky barrier diode is an unipolar device in which electrons serve as the main charge carriers for transporting current. The device has a low forward voltage drop and a fast switching. However, the leakage current of Schottky diodes increases as reverse bias increases because of the lowering of Schottky barrier under high electric field. To reduce the leakage current at the reverse bias, a high work function is usually used to provide a high Schottky barrier, which will in turn increase the forward voltage drop and turn-on power loss of the device. The Schottky diode with a trench structure is one of solutions proposed to compromise above mentioned trade-offs. A trench-ype Schottky dioe usually comprises a plurality of mesas separated by a plurality of trenches. A Schottky contact with a lower barrier formed on the mesa provides a low forward voltage drop, while a MOS structure or a Schottky contact with a higher barrier formed in the trenches shield the electric field on the low barrier contact and thus reduces the leakage current at the reverse bias.
A edge termination structure is usually incorporated in Schottky devices to prevent the premature breakdown due to surface field crowding around the edge of electrode. The edge termination structure may be a field plate, a junction termination extension (JTE) or a floating guard rings. JTE and floating guard rings form pn junctions by ion implantations around the edges of the device to perturb the surface electric field distribution and improve the blocking capability of the device. In SiC carbide devices, the ion implantation is usually implemented at up to several hundred ° C. and then post-annealed at a temperature above 1600° C. to activate the dopants, thus make it a costly process. Etch terminations such as bevels used in silicon thyristors require a large area and are also not applicable for devices without PNpn junctions.